hit the rock
1. To touch another person's fist with one's own in a display of celebration, solidarity, or friendship, or to solidify a deal or arrangement; to "fist-bump." Primarily heard in US. Hey man, how you been? Come here and hit the rock! The two hit the rock and sealed the deal.
2. To freebase crack cocaine. Primarily heard in US. It was when I found myself hitting the rock for five or six days straight that I decided to get professional help.